In this article

about_Operators

12/15/2009

5 minutes to read

In this article

Applies To: Windows PowerShell 2.0

TOPIC
about_Operators
SHORT DESCRIPTION
Describes the operators that are supported by Windows PowerShell.
LONG DESCRIPTION
An operator is a language element that you can use in a command or
expression. Windows PowerShell supports several types of operators to
help you manipulate values.
Arithmetic Operators
Use arithmetic operators (+, -, *, /, %) to calculate values in a command
or expression. With these operators, you can add, subtract, multiply, or
divide values, and calculate the remainder (modulus) of a division
operation.
You can also use arithmetic operators with strings, arrays, and hash
tables. The addition operator concatenates elements. The multiplication
operator returns the specified number of copies of each element.
For more information, see about_Arithmetic_Operators.
Assignment Operators
Use assignment operators (=, +=, -=, *=, /=, %=) to assign one or more
values to variables, to change the values in a variable, and to append
values to variables. You can also cast the variable as any Microsoft .NET
Framework data type, such as string or DateTime, or Process variable.
For more information, see about_Assignment_Operators.
Comparison Operators
Use comparison operators (-eq, -ne, -gt, -lt, -le, -ge) to compare values
and test conditions. For example, you can compare two string values to
determine whether they are equal.
The comparison operators include the match operators (-match, -notmatch),
which find patterns by using regular expressions; the replace operator
(-replace), which uses regular expressions to change input values; the
like operators (-like, -notlike), which find patterns using wildcard
characters (*); and the containment operators (-contains, -notcontains),
which determine whether a test value appears in a reference set.
They also include the bitwise operators (-bAND, -bOR, -bXOR, -bNOT) to
manipulate the bit patterns in values.
For more information, see about_Comparison_Operators
Logical Operators
Use logical operators (-and, -or, -xor, -not, !) to connect conditional
statements into a single complex conditional. For example, you can use a
logical -and operator to create an object filter with two different
conditions.
For more information, see about_Logical_Operators.
Redirection Operators
Use redirection operators (>, >>, 2>, 2>, and 2>&1) to send the output of
a command or expression to a text file. The redirection operators work
like the Out-File cmdlet (without parameters) but they also let you
redirect error output to specified files. You can also use the Tee-Object
cmdlet to redirect output.
For more information, see about_Redirection.
Split and Join Operators
The -split and -join operators divide and combine substrings. The -split
operator splits a string into substrings. The -join operator concatenates
multiple strings into a single string.
For more information, see about_Split and about_Join.
Type Operators
Use the type operators (-is, -isnot, -as) to find or change the .NET
Framework type of an object.
For more information, see about_Type_Operators.
Unary Operators
Use unary operators to increment or decrement variables or object
properties and to set integers to positive or negative numbers. For
example, to increment the variable $a from 9 to 10, you type $a++.
Special Operators
Use special operators to perform tasks that cannot be performed by the
other types of operators. For example, special operators allow you to
perform operations such as running commands and changing a value's data
type.
@( ) Array subexpression operator
Returns the result of one or more statements as an array.
If there is only one item, the array has only one member.
@(Get-WMIObject win32_logicalDisk)
& Call operator
Runs a command, script, or script block. The call operator, also known as
the "invocation operator," lets you run commands that are stored in
variables and represented by strings. Because the call operator does not
parse the command, it cannot interpret command parameters.
C:\PS> $c = "get-executionpolicy"
C:\PS> $c
get-executionpolicy
C:\PS> & $c
AllSigned
[ ] Cast operator
Converts or limits objects to the specified type. If the objects
cannot be converted, Windows PowerShell generates an error.
[datetime]$birthday = "1/20/88"
[int64]$a = 34
, Comma operator
As a binary operator, the comma creates an array. As a unary
operator, the comma creates an array with one member. Place the
comma before the member.
$myArray = 1,2,3
$SingleArray = ,1
. Dot sourcing operator
Runs a script in the current scope so that any functions,
aliases, and variables that the script creates are added to the current
scope.
. c:\scripts.sample.ps1
Note: The dot sourcing operator is followed by a space. Use the space to
distinguish the dot from the dot (.) symbol that represents the
current directory.
In the following example, the Sample.ps1 script in the current
directory is run in the current scope.
. .\sample.ps1
-f Format operator
Formats strings by using the format method of string
objects. Enter the format string on the left side of the operator
and the objects to be formatted on the right side of the operator.
C:\PS> "{0} {1,-10} {2:N}" -f 1,"hello",[math]::pi
1 hello 3.14
For more information, see the String.Format method
(http://go.microsoft.com/fwlink/?LinkID=166450) and
Composite Formatting (http://go.microsoft.com/fwlink/?LinkID=166451).
[ ] Index operator
Selects objects from indexed collections, such as arrays and
hash tables. Array indexes are zero-based, so the first object
is indexed as [0]. For arrays (only), you can also use negative
indexes to get the last values. Hash tables are indexed by key
value.
C:\PS> $a = 1, 2, 3
C:\PS> $a[0]
1
C:\PS> $a[-1]
3
C:\PS> (get-hotfix | sort installedOn)[-1]
C:\PS> $h = @{key="value"; name="Windows PowerShell"; version="2.0"}
C:\PS> $h["name"]
Windows PowerShell
C:\PS> $x = [xml]"<doc><intro>Once upon a time...</intro></doc>"
C:\PS> $x["doc"]
intro
-----
Once upon a time...
| Pipeline operator
Sends ("pipes") the output of the command that precedes it to the
command that follows it. When the output includes more than one object
(a "collection"), the pipeline operator sends the objects one at a time.
get-process | get-member
get-pssnapin | where {$_.vendor -ne "Microsoft"}
. Property dereference operator
Accesses the properties and methods of an object.
$myProcess.peakWorkingSet
(get-process powershell).kill()
.. Range operator
Represents the sequential integers in an integer array,
given an upper and lower boundary.
1..10
10..1
foreach ($a in 1..$max) {write-host $a}
:: Static member operator
Calls the static properties operator and methods of a .NET
Framework class. To find the static properties and methods of an
object, use the Static parameter of the Get-Member cmdlet.
[datetime]::now
$( ) Subexpression operator
Returns the result of one or more statements. For a
single result, returns a scalar. For multiple results, returns an
array.
$($x * 23)
$(Get-WMIObject win32_Directory)
SEE ALSO
about_Arithmetic_Operators
about_Assignment_Operators
about_Comparison_Operators
about_Logical_Operators
about_Type_Operators
about_Split
about_Join
about_Redirection